I think the Johnson bar controls the loco’s direction but
what do the injectors do ?
Is the smoke from the smoke stack a combination of smoke from the boiler fire and
the used steam from the cylinders ?
What are the small water pipes that drip water from either side under the cab for ?
Does a compound steam loco reuse the steam exaust for the second set of cylinders ?
Why does the engineer do a blow down ?
Do some locos use low pressure steam while others use high pressure ?
Thanks !
The injectors force water into the boiler against the boiler pressure. They use steam for this purpose.
Second question, you got it. The chuff you hear is steam released from the cylinders that is routed to a standpipe that is just below the aperture at the top of the smoke box from which the stack issues. Those chuffs of steam suck air into the firebox at the far end of the engine, thus improving the draft immensely. Provides more steam.
Those dripping pipes are the overflow from the injectors.
Yes, Mallet engines use the waste steam from the cylinders closer to the cab. That cooler and less dense steam is routed via conduit to the front, noticeably larger, cylinders. Those larger cylinders permit about the same amount of work from the waste steam as from the original steam used in the rear, smaller, “simple” steam cylinders. There is more cross-section to those larger pistons, so more work surface area for the cooler steam to apply force.
A blow down is meant to get rid of scale deposites left over as the water is replaced continuously, evaporates, and leaves increasing levels of mineralization in the water left to be heated in the boiler.
Yes, the earlier engines, as a rule, used lower pressure steam but mostly because of engineering and design, plus perhaps metallurgical limitations when they were designed and built. Later on, the super steam and high-speed engines of 1900-ish and beyond used superheaters in the smoke box, plus just bigger fireboxes and feedwater-water heaters, to increase the steam available. Since the boilers only got so much bigger, that meant a large increase in the steam pressure, often between 275-300 psi.
That is my understanding…undoubtedly there is room for improvement. [:)]
You can get all the information you could ever want from this web site
Have fun
The injector pumps water into the boiler from the tender. Because the boiler is under pressure, water can’t flow freely iinto it, so it has to be pumped under a higher pressure by the injector.
Yes, exhaust steam from the cylinders blows up the stack and draws the smoke with it.
Condensed steam from the injectors, dynamo, etc.
Yes, a compound articulated locomotive has larger cylinders on the front engine that re-uses the lower-pressure steam released from the rear engine’s cylinders. A simple articulated locomotive feeds high-pressure steam to both sets of equal-sized cylinders. Some engines were designed to operate as either simple or compound.
The fireman is the one who performs the blowdown of the mud ring. Dirt, minerals, and other contaminants in the water settle to the bottom of the boiler and must be blown out periodically so they don’t get into the cylinders, injectors, or other devices and clog them up.
Yes, different types of locomotives use different boiler pressures, but nearly all of them operate at a higher boiler pressure than any type of stationary boiler.
Thanks for all the answers !!!
I have seen photos of Locos pulling Trains with No smoke comming out of the stack
except a small white wisp
I think this is called “Having a feather in their stack”
Are they coasting when this happens ?
C&O Fan,
You have the ‘Johnson Bar’ correct. It allowed the engineer to set the valve travel for admitting steam to the pistons. Later engines had a ‘power’ reverse. I am not a steam expert(only 58!), but I have been around the modeling side for a while:
Injectors - Used to ‘inject’ fresh water from the tender into the boiler. Usually 2 of them on each engine. There may also be a feed water pump system to ‘pre-heat’ the cold tender water before it is pumped into the boiler.
Smoke Stack - At the bottom of the smoke box, there is an exhaust nozzle that the spent steam from the cylinders blows the exhaust up through the smoke box and out the stack. This is what gives a steamer that ‘chuffing’ sound. It also helps force the draft to pull the hot flue gases/smoke the boiler area and out of the engine through the smoke stack. There is also a smaller nozzle to blow steam directly from the boiler to force the drafting. Many times this is turned on in station areas when the engine is not running, and turned off when the train starts moving(and the exhaust ‘chuffs’ provide the draft…).
Dripping pipes - Depending on the engine, they could be from the injectors, water pump, or blow down trap. There is lots of places for things to ‘drip’…
Compound - Steam is first fed to the high pressure cylinders, then to the low pressure cylinders. Many early articulated steamers were ‘Compound’. The rear set of high pressue cylinders got feed directly from the boiler, and the exhausted steam was then fed to the larger low pressue cylinders in front.
Blow Down - this is a large valve that allows the engineer to exhaust steam through the blow down pipe. This is done to pull sediment/loose scale from the boiler.
Steam - Older
quote user=“C&O Fan”
Thanks for all the answers !!!
I have seen photos of Locos pulling Trains with No smoke comming out of the stack
except a small white wisp
I think this is called “Having a feather in their stack”
Are they coasting when this happens ?
If those are Norfolk and Western locomotives, they were frequently photographed standing still (prearrangement by the Company, or Company-approved, photographer.) Then the little wisp of ??? was added later with an airbrush.
Don’t know if this was also done by other railroads, but it might have been.
A loco which is, “Showing a white feather,” has the steam pressure right at the limit - the slightest increase will open the safety valve and dump a couple of PSI. The feather shows at the safety valve, not the stack.
I take exception to the poster who claimed that locomotive boilers were always higher pressure than stationary boilers. Stationary boilers with steam pressures at or close to 1000 PSI were common, as were marine boilers. The only railroad boiler which ever got into this realm was the B&W water-tube unit in N&W’s turboelectric unit, the Jawn Henry.
Chuck (modeling Central Japan in September, 1964)
Some images of steamers, such as the Pennsy J1, show a tiny plume of what appears to be steam rising from a small tube immediately aft of the stack. What are we seeing?
I think you’ll find this page immensely informative. It also includes animations of how various parts work
http://home.new.rr.com/trumpetb/loco/index.html
The dripping beneath the cab is attached to injectors. The injectors take water from the tender and inject it into the boiler.
This link includes really cool animations of how all the different configurations of valves work. You can adjust the Johnson bar and see how it causes a change in the driver movement.
Sometimes, yes. Other times, the engine is being operated by a good engineer and fireman, who know exactly how to use fuel. It’s not uncommon to see steam engines running without any smoke plume; in fact, some railroads preferred things that way (the N&W never wanted to see smoke coming out of the stack, as it was an indication that fuel was being used inefficiently. They also didn’t like to see a lot of whistle blowing for the same reason)
On the J-1s, that’s the exhaust for the turbogenerator. On some engines equipped with boosters in the trailing truck, that’s the common place to run the exhaust pipe for the booster. It’s a pretty common arrangement.
Ray, thanks!
-Crandell
This link displays a rough example of how many different types of engines work, gas, deisel, steam, etc.
http://www.keveney.com/Engines.html
[edit]
forgot to add that steam is about 1/2 way down the page
I was watching an on-line video of CPR 2816 this evening, and the tube that I spoke of is actually in front of the stack, and looks like it may have something to do with the feedwater heater. Is there a steam-driven pump in the Elesco housing?
Not only direction, but the steam cutoff - that is, for what percentage of the piston stroke is steam admitted to the cylinder. As the speed increases, the amount of steam sent to the cylinders is decreased, to where there is just enough steam being sent to the cylinders to maintain the desired speed.
They perform a kind of magical “bootstrap” operation to use the boiler’s steam to inject fresh water to the boiler to make more steam, through one-way valves called check valves.
Yes. The exhaust steam creates the draft through the fire by utilizing the “Venturi effect”. It is blown up the stack, creating a partial vacuum in the smokebox. This draws air through the grates in the firebox, and the resulting heat and smoke through the flues in the boiler and out the stack with the steam.
Probably the overflow pipes from the injectors.
Yes. Thus the term “compound”.
To eject scale and hard water deposits from the base ring of the boiler. This prevents a buildup which would reduce the steaming capacity of the boiler.
Yes. Most “modern” steam locomotives use superheated steam which gives it a higher effective working pressure. The steam is passed th
Possibly coasting, yes, but more likely there was a good fireman on duty. Railroads discouraged smoke for several reasons, among them being that the public didn’t like having their washing coated with soot from a passing train, and especially that smoke wastes fuel, which costs money. The white wisp isn’t smoke - it’s steam. Smoke is black. “Showing a feather” generally refers to the slight amount of steam escaping from the safety valves when they are right at the maximum pressure. A good place to be, as long as you don’t let the safeties blow. Blowing steam out the safeties wastes steam, which wastes the fuel used to create it, which, again, costs money.
It might be some sort of overflow exhaust for the Elesco, but I can’t be sure, since I can’t find a good shot of the engineer’s side of the smokebox from a slightly down angle. I took lots of shots of her in September, but all from the fireman’s side! (that side was lit properly)
They perform a kind of magical “bootstrap” operation to use the boiler’s steam to inject fresh water to the boiler to make more steam, through one-way valves called check valves.
Let me see, the boiler produces steam, part of which is used to power an injector which forces water into the boiler to produce steam, part of which is used to… Isn’t this a form of perpetual motion?
Just kidding…I think.
Ray
Ray, the thermal energy in the boiler is thousands of times what it takes at any one instant to run the injector. The whistle takes much more steam to run it than does the injector, and the whistle steam is lost to the atmosphere. At least the injector steam is partially recovered, although little as I understand it.
However, injecting cooler water into the boiler doesn’t do much good for steam production at the moment of injection. But, you must have water at the right level so that the crown sheet is never exposed. In simulators that I have seen, when you inject water the boiler temp drops a bit, and even the pressure. Maybe Mark Newton, if he is going to read this, might help us out a bit.